1. Field
The present application relates to a fuel cell.
2. Description of the Related Art
In general, a solid polymer-type fuel cell includes a solid polymer electrolyte membrane formed of a polymer ion exchange membrane. The fuel cell is equipped with an electrolyte membrane-electrode assembly (MEA) in which an anodic electrode is disposed on one of the surfaces of the solid polymer electrolyte membrane and a cathodic electrode is disposed on the other surface of the solid polymer electrolyte membrane. The anodic electrode and the cathodic electrode each include a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon).
The MEA sandwiched between separators (bipolar plates) constitutes a power generation cell (unit fuel cell). A particular number of power generation cells are stacked and used as a vehicle-mount fuel cell stack, for example.
A fuel cell often includes an inner manifold in order to supply reactant gas, namely, fuel gas and oxidant gas, to the anodic electrodes and the cathodic electrodes of the respective power generation cells that are stacked.
The inner manifold has reactant gas inlet manifold holes (fuel gas inlet manifold holes and oxidant gas inlet manifold holes) and reactant gas outlet manifold holes (fuel gas outlet manifold holes and oxidant gas outlet manifold holes) that penetrate in the stacking direction of the power generation cell. A reactant gas inlet manifold hole is in communication with the inlet side of a reactant gas flow channel (fuel gas flow channel or oxidant gas flow channel) through which reactant gas is supplied along the electrode surface, and a reactant gas outlet manifold hole is in communication with the outlet side of the reactant gas flow channel.
In this case, the reactant gas inlet manifold hole and the reactant gas outlet manifold hole are connected to the reactant gas flow channel via connecting flow channels that have parallel grooves and the like in order to smoothly and uniformly supply the reactant gas. In order to enable smooth sealing without clogging the connecting flow channels, a fuel cell is proposed in Japanese Patent No. 5824575, for example.
According to this fuel cell, the MEA is a resin-framed MEA that includes a resin frame member around the outer periphery of the MEA. The resin frame member has such an outer shape that the resin frame member is disposed on the inner side of the reactant gas manifold holes formed in the outer periphery of the metal separators. The resin frame member is equipped with a buffer portion positioned outside the power generation region and connected to the reactant gas flow channel and a part of the connecting flow channel (bridge portion) that connects the buffer portion to the reactant gas manifold hole.
The document describes that since a resin frame member having relatively high rigidity is used, the resin frame member is prevented from being deformed and clogging of the connecting flow channel can be reliably prevented with a simple and economic structure.